Traditional communications networks are increasingly being replaced and superseded by Packet Based Networks, especially those based on Internet Protocol (IP). These packet-based networks have different capabilities and constraints, accordingly the planning of the network is based on different criteria.
The criteria on which a network is planned depends on the requirements and the specification of the network. The requirements include features such as bearer traffic (to be described in greater detail below) both in the classical ATM domain and the IP packet domain. For example, the network may carry high priority voice and real time video traffic together with various forms of high and low priority data traffic. The specification of the network depends on the equipment, the gateways and connections between the equipment and the type of calls which are to be made. The different types of call includes, national, international, mobile, data, voice, fax and any combination thereof. The network may also need to provide wireless access to deliver wireless Internet services.
A particular problem in designing a network is that of reconciling a number of conflicting requirements. For example, high bandwidth capability and extensive availability of resources are inherently desirable features, but they must be traded off against the cost of providing such features. Similarly, a network may be designed for a particular level of traffic, but it is also desirable to provide for scaling of the network should the future growth of traffic exceed expected levels. The network may be required to carry a number of different types of traffic having different transport requirements and different priority classes. The network design may be further complicated by the need to provide interworking between devices supplied by different manufacturers, a so-call eclectic collection of devices. In practice there are a large number of requirements and specifications, some of which may be conflicting, and it is thus an onerous task to determine an optimum solution for each individual case.